Aberrometría corneal en el queratocono subclínico

Objetivo: Determinar parámetros aberrométricos de la córnea para la detección del queratocono subclínico. Métodos: Se realizó un estudio observacional, analítico de corte transversal que incluyó 36 pacientes con queratocono subclínico (grupo de estudio) y 36 estudiantes con córneas aparentemente sanas (grupo control), que asistieron a la consulta de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre mayo de 2018 y junio de 2022. Se analizaron topografía y aberrometría corneal con el tomógrafo corneal Pentacam AXL. Resultados: El grupo queratocono subclínico mostró valores similares para la queratometría, asfericidad corneal, paquimetría y el valor total de desviación en comparación con el grupo normal. Hubo diferencias estadísticamente significativas en los parámetros aberrométricos, como el coma a 90º (Z3 -1), y la raíz cuadrada media de las aberraciones de alto orden, de cara anterior, posterior y total corneal, en queratocono subclínico en comparación con el grupo normal. El coma posterior a 90º presentó un área bajo la curva (0,894) mayor dentro de las aberrometrías, con un punto de corte de -0,013 μm, con sensibilidad del 86,1 % y especificidad del 88,9 %. Conclusiones: El coma posterior a 90º (parámetro aberrométrico) presenta una alta sensibilidad y especificidad para el diagnóstico de queratocono subclínico, mediante el análisis tomográfico Pentacam AXL.

Objective: To determine corneal aberrometric parameters for the detection of subclinical keratoconus. Methods: An observational, analytical, cross-sectional study was performed including 36 patients with subclinical keratoconus (study group) and 36 students with apparently healthy corneas (control group), who attended the cornea consultation at the Cuban Institute of Ophthalmology Ramón Pando Ferrer, between May 2018 and June 2022. Corneal topography and aberrometry were analyzed with the Pentacam AXL corneal tomographer. Results: The subclinical keratoconus group showed similar values for keratometry, corneal asphericity, pachymetry and total deviation value compared to the normal group. There were statistically significant differences in aberrometric parameters, such as coma at 90° (Z3-1), and root mean square of high-order anterior, posterior and total corneal aberrations in subclinical keratoconus compared to the normal group. The 90° posterior coma presented a higher area under the curve (0.894) within the aberrometries, with a cutoff point of -0.013 μm, with sensitivity of 86.1 % and specificity of 88.9 %. Conclusions: Coma posterior to 90º (aberrometric parameter) presents high sensitivity and specificity for the diagnosis of subclinical keratoconus, using Pentacam AXL tomographic analysis.

Densitometría corneal en el queratocono

Objetivo: Evaluar la densitometría corneal en pacientes con queratocono. Métodos: Se realizó un estudio observacional descriptivo de corte transversal que incluyó 90 pacientes con queratocono (grupo de estudio) y 30 estudiantes con córneas aparentemente sanas (grupo control), que asistieron a la consulta de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre mayo del 2018 y junio del 2019. Se seleccionó el ojo derecho de cada caso. Se analizaron densitometría corneal con el tomógrafo corneal Pentacam AXL. Resultados: La densitometría fue mayor en el queratocono respecto a la córnea aparentemente sana, de 0 a 2 mm, en la capa anterior, central, y posterior, respectivamente (p < 0,001). La densitometría aumentó en los 0 a 2 mm en la capa anterior en el grupo moderado y en el grupo avanzado (p < 0,001), y entre los 2-6 mm en la capa central, de 10,86 ± 0,54 en el control, en el queratocono avanzado a 12,35 ± 1,16 y en el moderado a 12,16 ± 1,45 (p < 0,001). La densitometría aumentó en el avanzado de 27,64 ± 3,81, de 22,77 ± 2,14 en el leve, y de 24,04 ± 2,83 en el moderado y en los 0-2 mm, en la capa anterior. Conclusiones: La densitometría es mayor en la córnea queratocónica respecto a la córnea aparentemente sana, además que se incrementa al aumentar la gravedad del queratocono en el área central.

Objective: To evaluate corneal densitometry in patients with keratoconus. Methods: A cross-sectional descriptive observational cross-sectional study was performed including 90 patients with keratoconus (study group) and 30 students with apparently healthy corneas (control group), who attended the cornea consultation at the Cuban Institute of Ophthalmology Ramón Pando Ferrer, between May 2018 and June 2019. The right eye of each case was selected. Corneal densitometry was analyzed with the Pentacam AXL corneal tomographer. Results: Densitometry was higher in keratoconus relative to apparently healthy cornea, from 0 to 2 mm, in the anterior, central, and posterior layer, respectively (p < 0.001). Densitometry increased in the 0 to 2 mm in the anterior layer in the moderate group and in the advanced group (p < 0.001), and between 2-6 mm in the central layer, from 10.86 ± 0.54 in the control, in the advanced keratoconus to 12.35 ± 1.16 and in the moderate to 12.16 ± 1.45 (p < 0.001). Densitometry increased in advanced from 27.64 ± 3.81, from 22.77 ± 2.14 in mild, and from 24.04 ± 2.83 in the moderate and 0-2 mm, in the anterior layer. Conclusions: Densitometry is higher in the keratoconic cornea with respect to the apparently healthy cornea, moreover it increases with increasing severity of keratoconus in the central area.

Effect of mydriatic eye drops (combined 0.8% tropicamide and 5% phenylephrine) on the measurements of corneal parameters using Pentacam

Purpose: The purpose of the study is to investigate the effects of combined 0.8% tropicamide and 5% phenylephrine on the corneal parameters using Pentacam. Methods: The study was performed on 200 eyes of 100 adult patients visiting the ophthalmology clinic for evaluation of refractive errors or cataract screening. Mydriatic drops (Tropifirin; Java, India) containing tropicamide 0.8%, phenylephrine hydrochloride 5%, and chlorbutol 0.5% (as a preservative) were instilled into the eyes of the patients three times every 10 minutes. The Pentacam was repeated after 30 minutes. The measurement data of various corneal parameters from different Pentacam displays (keratometry, pachymetry, densitometry, and Zernike analysis) was manually compiled on an Excel spreadsheet and analyzed using Statistical Package for the Social Sciences (SPSS) 20 software. Results: Analysis of Pentacam refractive maps revealed a statistically significant increase (P < 0.05) in the values of radius peripheral (cornea front), pupil center Pachymetry, pachymetry apex, thinnest location Pachymetry, and cornea volume. However, pupil dilation did not affect the Q?value (asphericity). Analysis of the densitometry values revealed significant increase in all zones. Aberrations maps revealed statistically significant increase in the value of spherical aberration after the induction of mydriasis, but the values of Trefoil 0º, Trefoil 30º, Koma 90º, and Koma 0º were not affected significantly. We did not observe any untoward effect of the drug, except transient blurring of vision. Conclusion: The current study showed that routine mydriasis in the eye clinics leads to a significant increase in various corneal parameters including corneal pachymetry, cornea densitometry, and spherical aberration as measured by Pentacam, which can influence the decision?making in the management of various corneal diseases. The ophthalmologists should be aware of these issues and make adjustments in their surgical planning accordingly

Repetibilidade do estudo tomográfico da córnea com Scheimpflug rotacional, em olhos normais, olhos com ceratocone e olhos com ceratocone operados por crosslinking / Repeatability of the tomographic study of the cornea with a rotational Scheimpflug in normal eyes, eyes with keratoconus and eyes with crosslinking for keratoconus

RESUMO Objetivo Avaliar a precisão da tomografia corneana com imagens de Scheimpflug (Pentacam® AXL, OCULUS, Wetzlar, Alemanha) nos padrões de escaneamento com 25 e 50 imagens, verificando sua repetibilidade e reprodutibilidade em olhos normais, com ceratocone e com ceratocone após crosslinking. Métodos Estudo prospectivo, transversal, misto, no qual foram incluídos os pacientes que tinham córneas normais, ou com ceratocone; e não tinham realizado cirurgias corneanas, com exceção do crosslinking. Foram excluídos os pacientes que tivessem realizado outras cirurgias, como implante de anel intracorneano ou transplante de córnea. Foram realizadas três medidas com 25 imagens e três medidas com 50 imagens em cada olho incluído no estudo. Resultados O estudo avaliou 54 olhos de 41 pacientes. Destes, dez (18,52%) olhos eram com córneas normais e sem cirurgia ocular prévia aleatoriamente selecionados de 5 pacientes; 22 (40,74%) olhos aleatoriamente selecionados de 18 pacientes com ceratocone, sem cirurgia ocular prévia; e 22 (40,74%) olhos com ceratocone de 18 pacientes operados por crosslinking. No estudo da repetibilidade, percebemos uma maior variação de valores em todos os índices nos pacientes com ceratocone comparados aos de pacientes com olhos normais, em grande parte dos parâmetros analisados. Conclusão Não houve diferença significativa entre os métodos de escaneamento por 25 e 50 imagens, sendo o escaneamento por 25 imagens mais conveniente. A presença de ceratocone teve impacto negativo na repetibilidade de ambos os tipos de exame, e foi grande a concordância entre os métodos nos três grupos estudados. O coeficiente de repetibilidade permite considerar a relevância clínica dos dados para avaliar a progressão de ceratocone.

ABSTRACT Objective To evaluate the accuracy of corneal tomography with Scheimpflug images (Pentacam® AXL, OCULUS, Wetzlar, Germany) in scanning patterns with 25 and 50 images, by analyzing their repeatability and reproducibility in normal eyes, eyes with keratoconus and with keratoconus after crosslinking. Methods Prospective, cross-sectional, mixed study including patients who had normal corneas, or who had keratoconus, who had not undergone corneal surgery, with the exception of crosslinking. Patients who had undergone surgery for intracorneal ring implantation or corneal transplantation were excluded. Three measurements were performed with 25 images and three measurements were performed with 50 images on each eye included in the study. Results The study evaluated a total of 54 eyes of 41 patients. Of these, 10 (18.52%) eyes had normal corneas, without previous eye surgery, 22 (40.74%) were eyes with keratoconus, without previous eye surgery, and 22 (40.74%) were eyes with keratoconus, with crosslinking for keratoconus. In the study of repeatability, we noticed a greater variation of values in all indices in patients with KC compared to those with normal eyes, in most of the parameters analyzed. Conclusion There is no significant difference between the scanning methods with 25 and 50 images. However, 25 scans has advantages that make it the main method suggested. The presence of keratoconus has a negative impact on the repeatability of both types of examination, and there is great agreement between the methods in the three groups studied. The high repeatability coefficient in some parameters suggests that these data should be used with care in the assessment of keratoconus progression.

Research of first-degree relatives of keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#Keratoconus(KC)is a progressive disease characterized by gradual corneal thinning and ectasia, resulting in irregular astigmatism, myopia, and mild to severe visual impairment. Although the pathogenesis of KC is still unclear, twin studies and family-based studies have identified that the occurrence of KC is closely related to genetic factors. First-degree relatives of KC patients including their parents, siblings and offspring are very important for the family aggregation analysis and polygenic analysis of diseases. This review summarized the current situation of clinical and genetic research about first-degree relatives of KC patients, hoping to deepen the understanding of clinical manifestations and genetic characteristics of first-degree relatives of KC, and to provide new ideas for exploring the role of genetic and environmental factors in the pathogenesis of KC.

Resultados tomográficos luego del tratamiento del queratocono con crosslinking corneal / Tomographic results after the treatment of queratocono with corneal crosslinking

RESUMEN Objetivos: Determinar las modificaciones tomográficas en pacientes con queratocono tratados con crosslinking corneal en 8 años de evolución. Métodos: Se realizó un estudio descriptivo, longitudinal y retrospectivo de 58 ojos pertenecientes al mismo número de pacientes con queratocono progresivo, operados con crosslinking corneal en el año 2009 en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer". El análisis estadístico se realizó con la prueba t para datos pareados, con significación del 95 por ciento. Resultados: La media final de la SimK1, SimK2, la queratometría media y el cilindro topográfico fueron de 44,57 ± 3,08; 47,75 ± 3,96; 46,16 ± 3,28 y 3,45 ± 2,35 dioptrías respectivamente. El factor Q, la curvatura mínima sagital, el índice de variación de superficie, el índice de asimetría en elevación y el índice de queratocono finales fueron -0,49 ± 0,34; 6,85 ± 0,73; 51,00 ± 20,09; 27,38 ± 12,77 y 1,05 ± 0,12 respectivamente. La media final de volumen corneal, la elevación posterior, la paquimetría central, el ápex y el punto más fino fueron 57,63 ± 2,45 mm3; 36,22 ± 27,42 µm; 458,97 ± 65,03 µm; 460,34 ± 64,90 µm y 454,79 ± 69,36 µm. Predominó la córnea prolata con 62,1 por ciento. Conclusiones: La reducción de las queratometrías, del cilindro topográfico y de los índices variación de superficie, asimetría en elevación y queratocono con tendencia a la estabilización demostraron una reducción de la severidad del queratocono(AU)

ABSTRACT Objectives: Determine the tomographic modifications in patients with keratoconus treated with corneal crosslinking (CXL) in 8 years of evolution, in the Cuban Institute of Ophthalmology "Ramón Pando Ferrer". Methods: A descriptive, longitudinal and retrospective study was conducted of 58 eyes of 58 patients with progressive keratoconus, operated with corneal crosslinking in 2009. The statistical analysis was performed with the T-Test for paired data, with a significance of 95 percent. Results: The final mean of the SimK1, SimK2, KM and the topographic cylinder were 44,57 ± 3,08 D; 47,75 ± 3,96 D; 46,16 ± 3,28 D and 3,45 ± 2,35 D respectively. The final factor Q, Rmin, ISV, IHA and the KI index were -0,49 ± 0,34; 6,85 ± 0,73; 51,00 ± 20,09; 27,38 ± 12,77 and 1,05 ± 0,12 respectively. The final mean corneal volume, posterior elevation, central pachymetry, apex and finest point were 57,63 ± 2,45 mm3; 36,22 ± 27,42 µm; 458,97 ± 65,03 µm; 460,34 ± 64,90 µm and 454,79 ± 69,36 µm. The prolata cornea predominated with 62,1 percent. Conclusions: The reduction in keratometry, topographic cylinder and ISV, IHA, and KI indexes with a tendency to stabilization showed a reduction in severe keratoconus(AU)

Dynamic corneal deformation response and integrated corneal tomography

Measuring corneal biomechanical properties is still challenging. There are several clinical applications for biomechanical measurements, including the detection of mild or early forms of ectatic corneal diseases. This article reviews clinical applications for biomechanical measurements provided by the Corvis ST dynamic non contact tonometer

Cornea and anterior eye assessment with placido-disc keratoscopy, slit scanning evaluation topography and scheimpflug imaging tomography

Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple and several devices and technologies allow to explore and to manage patients. The purpose of this special issue is to present and also to update in the evaluation of cornea and ocular surface and this second part, reviews a description of the corneal topography and tomography techniques, providing updated information of the clinical recommendations of these techniques in eye care practice. Placido-based topographers started an exciting anterior corneal surface analysis that allows the development of current corneal tomographers that provide a full three-dimensional reconstruction of the cornea including elevation, curvature, and pachymetry data of anterior and posterior corneal surfaces. Although, there is not an accepted reference standard technology for corneal topography description and it is not possible to determine which device produces the most accurate topographic measurements, placido-based topographers are a valuable technology to be used in primary eye care and corneal tomograhers expanding the possibilities to explore cornea and anterior eye facilitating diagnosis and follow-up in several situations, raising patient follow-up, and improving the knowledge regarding to the corneal anatomy. Main disadvantages of placido-based topographers include the absence of information about the posterior corneal surface and limited corneal surface coverage without data from the para-central and/or peripheral corneal surface. However, corneal tomographers show repeatable anterior and posterior corneal surfaces measurements, providing full corneal thickness data improving cornea, and anterior surface assessment. However, differences between devices suggest that they are not interchangeable in clinical practice.

Corneal biomechanical features in patients with ankylosing spondylitis / Características biomecânicas da córnea entre pacientes com espondilite anquilosante

ABSTRACT Purpose: To evaluate the corneal biomechanical features and central corneal thickness in ankylosing spondylitis patients and to evaluate correlations of these parameters with disease activity. Methods: The study included 51 patients diagnosed with ankylosing spondylitis (mean age, 40.80 ± 13.15 years; range, 18-72 years) and 34 age- and sex-matched healthy controls (mean age, 42.00 ± 12.32 years; range, 18-60 years). All underwent a complete ophthalmological and physical examination, including visual acuity testing and biomicroscopic anterior and posterior segment examinations. Corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure, and corneal compensated intraocular pressure were evaluated with an ocular response analyzer, and the central corneal thickness was measured with Sirius® corneal tomography. The Bath Ankylosing Spondylitis Disease Activity Index, Functional Index, and Metrology Index scores were recorded. Results: In the ankylosing spondylitis patients, the mean disease duration was 7.73 ± 6.05 (range, 1-30) years. There was no statistically significant difference between the patients and controls in the corneal biomechanical features. The Goldmann-correlated intraocular pressure and corneal compensated intraocular pressure both showed positive correlations with age (p=0.003 and p=0.001, res­pectively). There was a negative correlation between corneal hysteresis and disease duration (p=0.002), and between central corneal thickness and the Bath Ankylosing Spondylitis Metrology Index score (p=0.003). Conclusion: This study demonstrated a significant negative correlation between corneal hysteresis and disease duration in ankylosing spondylitis patients. Furthermore, the central corneal thickness value decreased with an increase in Bath Ankylosing Spondylitis Metrology Index score, which may result in an underestimate of intraocular pressure readings and thus an inaccurate risk assessment of glaucoma.

RESUMO Objetivo: Avaliar as características biomecânicas da córnea e espessura central da córnea em pacientes com espondilite anquilosante e analisar a correlação destes parâmetros no grupo de estudo com a atividade da doença. Métodos: Foram incluídos no estudo 51 pacientes com diagnóstico de espondilite anquilosante e 34 controles saudáveis com idade e sexo. Todos os sujeitos foram submetidos a um exame oftalmológico e físico completo, incluindo exames de acuidade visual, exames de segmento anterior e posterior biomicroscópicos. Foram avaliados o coeficiente de resistência da córnea, a pressão intraocular correlacionada com Goldmann e a pressão intraocular compensada da córnea com o analisador de resposta ocular, a espessura corneana central com a tomografia corneana pelo Sirius®. Se o índice de atividade da doença de espondilite anquilosante de banho, o índice funcional de espondilite anquilosante de banho, o índice de metrologia de espondilite anquilosante de banho. Resultados: Foram incluídos no estudo 51 pacientes com idade média de 40,80 ± 13,15 (intervalo: 18-72) anos e 34 casos de controle com idade média de 42,00 ± 12,32 (intervalo: 18-60) anos. No grupo espondilite anquilosante a duração média da doença foi de 7,73 ± 6,05 (1,00-30,00) anos. Não houve diferença estatisticamente significante entre dois grupos quanto às características biomecânicas da córnea. Na análise de correlação, no grupo de estudo; pressão intraocular correlacionada com Goldmann e pressão intraocular compensada da córnea estavam positivamente correlacionados com a idade (p=0,003, p=0,001, respectivamente). Houve uma correlação negativa entre a duração da doença e CH (p=0,002), e entre índice de metrologia de espondilite anquilosante de banho e espessura corneana central (p=0,003). Conclusão: Este estudo demonstrou correlação negativa significativa entre a duração da doença e a histerese corneal em pacientes com espondilite anquilosante. Além disso, com um aumento na pontuação de índice de metrologia de espondilite anquilosante de banho, o valor de espessura corneana central também estava di­minuindo o que pode causar uma diminuição nas leituras de pressão intraocular artificialmente e resultar em avaliação de risco imprecisa de glaucoma.

Hipertensão ocular mascarada por edema de córnea após cirurgia da catarata / Ocular hipertension confounded by corneal edema after cataract surgery

Com base em modelos matemáticos e estudos experimentais estima-se que as medidas da PIO sejam linearmente hiperestimadas em córneas com maior espessura e menor ceratometria por meio de tonometria de aplanação de Goldmann (TAG). Entretanto, tal influência se dá de uma maneira mais complexa que a prevista por estes parâmetros geométricos, sendo diretamente relacionada com propriedades biomecânicas. O sistema de não contato ORA (Ocular response analyzer Reichert) permite estudo das propriedades biomecânicas juntamente com a medida pressórica calibrada para a TAG e a compensada da córnea. Adicionalmente, o estudo tomográfico com reconstrução tridimensional do mapa paquimétrico caracteriza a córnea de forma mais completa que a ceratometria anterior e espessura central. Neste artigo, relatamos um caso de dor ocular, fotofobia e baixa visão, 28 dias após cirurgia de facoemulsificação com implante de lente intraocular sem complicações em paciente feminina de 81 anos. Na primeira visita da paciente, enquanto a TAG era de 16 mmHg, o valor da PIO compensada da córnea (PIOcc), obtido com o ORA, era 25,6 mmHg. A histerese e fator de resistência da córnea eram baixos, 4,1 e 6,1mmHg respectivamente, apesar da paquimetria central ser relativamente mais elevada, de 601 micra. O padrão de distribuição espacial da espessura era atenuado, compatível com edema corneano que era observado também por meio das imagens de Scheimpflug (Pentacam). Com base nestes dados, foi feito diagnóstico de quadro de uveíte hipertensiva, associado à edema corneano, instituindo-se tratamento tópico com combinação fixa de maleato de timolol e brimonidina associado ao acetato de prednisolona. Três semanas após, a paciente apresentou-se com grande melhora da acuidade visual, resolução do edema corneano, e dos sintomas, normalizando os parâmetros biomecânicos, geométricos da córnea e de PIO.

Goldmann applanation tonometry (GAT) overestimates intraocular pressure (IOP) measurements in cases with thick and flatter corneas. This is thought to occur linearly based on mathematical and on experimental studies. However, such influence does exist, but this is more complex than the one anticipated by pachymetry and keratometry because it is related to corneal biomechanical properties. The ocular response analyzer (ORA Reichert) provides the data related to the biomechanical properties of the cornea along with the IOP measurements that are calibrated for correlating to the Goldmann applanation and also compensated from corneal properties. Also corneal tomography with a pachymetric map evaluation characterizes the cornea beyond central thickness and anterior curvature. In this article, we report a case of a 77 years old female patient with low vision, photofobia and ocular pain 28 days after phacoemulsification and intraocular lens implant. In the first visit, GAT was 14mmHg, while IOPcc (ORA corneal compensated IOP) was 25,6mmHg. Corneal hysteresis and resistance factor were low: 4,1 and 6,1mmHg respectively despite a central thickness of 601 micron. Corneal thickness spatial profile was attenuated with an edematous pattern that was also observed by the Scheimpflug images (Pentacam). Hypertensive uveitis was diagnosed and the patient was started on a fixed combination of timolol and brimonidine associate with prednisolone acetate. Three weeks after, the patient referred resolution of photofobia and marked improvement of vision. Clinically, edema was resolved as observed by corneal tomographyc and biomechanical findings.